I have had a look at the page on the wiki dedicated to this router, but don't see any installation instructions — at least, none I would be able to follow.

I have no experience in installing firmware onto routers, and would really appreciate it if any of you could help me out.

I found an old BT Home Hub 3.0 Type A router in the cupboard and would like to install OpenWrt on it to replace the router we are currently using which suffers very badly from bufferbloat.

Can anyone provide step-by-step instructions as to what I should do to install the appropriate OpenWrt onto it?

My starting point: factory-reset home hub and 15" Macbook in hands, with another router (technicolor TG589vac) running downstairs providing me with this internet connection.

*bump*

There is no simple way, you need to follow the wiki (which involves pretty small scale soldering, the serial console and a rather high chance of bricking it terminally) - if the wiki sounds too difficult for you, then it probably is.